Several uncontrolled studies report improvement in lung function, gas exchange, and exercise capacity after bilateral lung volume reduction surgery (LVRS). We recruited 200 patients with severe chronic obstructive pulmonary disease (COPD) for a prospective randomized trial of pulmonary rehabilitation versus bilateral LVRS with stapling resection of 20 to 40% of each lung. Pulmonary function tests, gas exchange, 6-min walk distance, and symptom-limited maximal exercise testing were done in all patients at baseline and after 8 wk of rehabilitation. Patients were then randomized to either 3 additional months of rehabilitation or LVRS. Thirty-seven patients met study criteria and were enrolled into the trial. Eighteen patients were in the medical arm; 15 of 18 patients completed 3 mo of additional pulmonary rehabilitation. Thirty-two patients underwent LVRS (19 in the surgical arm, 13 crossover from the medical arm). After 8 wk of pulmonary rehabilitation, pulmonary function tests remained unchanged compared with baseline data. However, there was a trend toward a higher 6-min walk distance (285 +/- 96 versus 269 +/- 91 m, p = 0.14) and total exercise time on maximal exercise test was significantly longer compared with baseline values (7.4 +/- 2.1 versus 5.8 +/- 1.7 min, p < 0.001). In 15 patients who completed 3 mo of additional rehabilitation, there was a trend to a higher maximal oxygen consumption (V O(2)max) (13.3 +/- 3.0 versus 12.6 +/- 3.3, p < 0.08). In contrast, at 3 mo post-LVRS, FVC (2.79 +/- 0.59 versus 2.36 +/- 0.55 L, p < 0.001) and FEV(1) (0.85 +/- 0.3 versus 0.65 +/- 0.16 L, p < 0.005) increased whereas TLC (6.53 +/- 1.3 versus 7.65 +/- 2.1 L, p < 0.001) and residual volume (RV) (3.7 +/- 1.2 versus 4.9 +/- 1.1 L, p < 0.001) decreased when compared with 8 wk postrehabilitation data. In addition, Pa(CO(2)) decreased significantly 3 mo post-LVRS compared with 8 wk postrehabilitation. Six-minute walk distance (6MWD), total exercise time, and V O(2)max were higher after LVRS but did not reach statistical significance. However, when 13 patients who crossed over from the medical to the surgical arm were included in the analysis, the increases in 6MWD (337 +/- 99 versus 282 +/- 100 m, p < 0.001) and V O(2)max (13.8 +/- 4 versus 12.0 +/- 3 ml/kg/min, p < 0.01) 3 mo post-LVRS were highly significant when compared with postrehabilitation data. The Sickness Impact Profile (SIP), a generalized measure of quality of life (QOL), was significantly improved after 8 wk of rehabilitation and was maintained after 3 mo of additional rehabilitation. A further improvement in QOL was observed 3 mo after LVRS compared with the initial improvement gained after 8 wk of rehabilitation. There were 3 (9.4%) postoperative deaths, and one patient died before surgery (2.7%). We conclude that bilateral LVRS, in addition to pulmonary rehabilitation, improves static lung function, gas exchange, and QOL compared with pulmonary rehabilitation alone. Further studies need to evaluate the risks, benefits, and durability of LVRS over time.
The purpose of this study was to investigate the relationship between nutrition knowledge and body mass index (BMI). The General Nutrition Questionnaire was distributed to 500 individuals on the database of a large general practice. Results demonstrated that there was no significant correlation between levels of nutrition knowledge and BMI; however, a high level of nutrition knowledge was found among the sample. This suggests that a knowledge deficit may not be the most significant factor preventing overweight individuals from adopting a healthier diet and questions the utility of purely educational approaches to dietary behaviour change. Evidence-based health behaviour change techniques are discussed.
Since lung volume reduction surgery (LVRS) reduces end-expiratory lung volume, we hypothesized that it may improve diaphragm strength. We evaluated 37 patients for pulmonary rehabilitation and LVRS. Before and 8 wk after pulmonary rehabilitation, 24 patients had spirometry, lung volumes, diffusion capacity, incremental symptom limited maximum exercise test, 6-min walk test, maximal static inspiratory and expiratory mouth pressures, and transdiaphragmatic pressures during maximum static inspiratory efforts and bilateral supramaximal electrophrenic twitch stimulation measured. Twenty patients (including 7 patients who crossed over after completing pulmonary rehabilitation) had baseline measurements postrehabilitation, and 3 mo post-LVRS. Patients were 58 +/- 8 yr of age, with severe COPD and hyperinflation (FEV1, 0.69 +/- 0.21 L; RV, 4.7 +/- 1.4 L). Nineteen patients had bilateral LVRS performed via median sternotomy and stapling, and 1 patient had unilateral LVRS via thorascopy with stapling. After rehabilitation, spirometry and DL(CO)/VA were not different, and lung volumes showed a slight worsening in hyperinflation. Gas exchange, 6-min walk distance, maximum oxygen uptake (VO2max), and breathing pattern during maximum exercise did not change after rehabilitation, but total exercise time was significantly longer. Inspiratory muscle strength (PImax, Pdi(max combined), Pdi(max sniff), Pdi(max), Pdi(twitch)), was unchanged after rehabilitation. In contrast, after LVRS, FVC increased 21%, FEV1 increased 34%, TLC decreased 13%, FRC decreased 23%, and FRC(trapped gas) and RV decreased by 57 and 28%, respectively. PCO2 was lower (44 +/- 6 versus 48 +/- 6 mm Hg, p < 0.003) and 6-min walk distance increased (343 +/- 79 versus 250 +/- 89 m, p < 0.001), as did total exercise time during maximum exercise (9.2 +/- 1.9 versus 6.9 +/- 2.7 min, p < 0.01). Minute ventilation (29 +/- 8 versus 21 +/- 6 L/min, p < 0.001) and tidal volume (1.0 +/- 0.33 versus 0.84 +/- 0.25 L, p < 0.001) during maximum exercise increased whereas respiratory rate was lower (28 +/- 6 versus 32 +/- 7 breaths/min, p < 0.02). Measurements of respiratory muscle strength (PImax, 74 +/- 28 versus 50 +/- 18 cm H2O, p < 0.002; Pdi(max combined), 80 +/- 25 versus 56 +/- 29 cm H2O, p < 0.01; Pdi(max sniff), 71 +/- 7 versus 46 +/- 27 cm H2O, p < 0.01; Pdi(twitch), 15 +/- 5 versus 7 +/- 5 cm H2O, p < 0.01) were all greater post-LVRS. Inspiratory muscle workload as measured by Pdi TTI was lower following LVRS (0.07 +/- 0.02 versus 0.09 +/- 0.03, p < 0.03). On multiple regression analysis, increases in PImax correlated significantly with decreases in RV and FRC(trapped gas) after LVRS (r = 0.67, p < 0.03). We conclude that LVRS significantly improves diaphragm strength that is associated with a reduction in lung volumes and an improvement in exercise performance. Future studies are needed to determine the relationship and stability of these changes over time.
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